ECR International Utica Boilers UB90-50 Installation, Operation & Maintenance Manual page 26

Figure 15 - Concentric Vent Terminations
1" (25.4mm)
Maximum
Combustion
Air
1" (25.4mm)
Maximum
12" (305mm) Minimum
* See Note
Below
Vent
Combustion
Air
*Must be less than 4" (102mm) or greater than 24"
(610mm) Horizontal distance between end bells of each air
intake to prevent flue gas recirculation.
Figure 16 - Concentric Vent
ELBOW
A
(FIELD SUPPLIED)
STRAP
B
(FIELD SUPPLIED)
C 1" (26mm) Max.
COMBUSTION AIR AND VENT PIPE
Vent
Overhang
36"(0.9m) Minimum
Maintain 12"
Maintain US 12"(305mm)
clearance above
Canada 18" (457mm)
highest anticipated
clearance above highest
snow level or grade
anticipated snow level or
grade
Figure 17 - Concentric Vent Roof Installation
MAINTAIN 12 IN.
26
P/N 240010135 Rev. D [04/15/2017]